Organic Light Emitting Display (OLED) has the advantages of self-luminous, low driving voltage, high luminous efficiency, short response time, sharpness and contrast, nearly 180° viewing angle, wide temperature range, flexible display and large-area full-color display. It is recognized as the most promising display device in the industry.
The lighting principle of the OLED device is: the semiconductor material and the organic light emitting material cause light emission through the carrier injection and recombination driven by the electric field. Specifically, the OLED device usually adopts an indium tin oxide (ITO) electrode and a metal electrode as the anode and the cathode of the device respectively. Under a certain voltage, electrons and holes are injected into the electron transport layer and the hole transport layer from the cathode and the anode, respectively, and the electrons and holes migrate to the light-emitting layer through the electron transport layer and the hole transport layer, respectively, and meet in the light-emitting layer to form excitons and excite the light-emitting molecules that emit visible light through radiation relaxation.
Quantum dots (QDs) are nanocrystalline particles with a radius less than or close to the Boltz excimer radius and typically have a particle size between 1-20 nm. Quantum dots have a quantum confinement effect that emits fluorescence when excited. Moreover, quantum dots have unique luminescence properties such as wide excitation peak width, narrow emission peak and tunable luminescence spectrum, which make them promising applications in the field of photo-luminescence. Quantum dot light-emitting diode (QLED) is an electroluminescent device using quantum dot as a light-emitting layer. A quantum dot light-emitting layer is introduced between different conductive materials to obtain light of a desired wavelength. After more than two decades of development, quantum dot light-emitting diodes have become potential competitors for the next generation of display technologies due to their tunable size, tunable wavelength, half-width of the emission spectrum very narrow, large color gamut, high electroluminescence efficiency and reduced loss in solution process.
However, the QLED device is very sensitive to water and oxygen, and is highly susceptible to water and oxygen in the surrounding environment to cause device failure. Therefore, the QLED device needs a very high hermetic package structure. However, the high hermetic package structure will lead to the device cooling difficulties, which seriously hampered the efficiency and life expectancy. Therefore, how to ensure that the device has both sealing and heat dissipation has become an urgent problem to be solved in the package structure.